Do endophytic fungi grow through their hosts systemically?

Endophyte fungi are ubiquitous within vascular plants and recent evidence suggests that they have a number of effects on other organisms that attack those plants, such as insects and pathogens. Endophytes produce an array of metabolites in culture and it is possible that these fungi could be used in targeted programmes of application to plants, to provide a degree of pest protection. Such programmes would be most effective if the fungi grew systemically through their hosts. To date, evidence for systemic growth is equivocal and the aim of this study was to determine whether systemic growth occurs, through a detailed study of endophytes in one host plant species. We isolated a number of endophytes from the forb Silene dioica and examined fungal interactions in dual culture. We found very little evidence for any systemic growth within leaves and none within plants. Antagonistic interactions between fungi were extremely common, suggesting that any systemic effects of these fungi on other organisms are likely to be due to chemical movement, not fungal growth.